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Category: Vectors

Ross River Virus (RRV), a zoonotic alpha virus, is spread by a wide range of mosquitoes, including the Culex and Aedes mosquitoes. Queensland seems to be the worst hit with this disease, with as many as 3292 cases being reported till the end of March 2015. New South Wales has also seen a surge in the number of RRV cases as over 320 cases were registered by the middle of March 2015. It has rapidly emerged to be the most important vector borne disease in Australis, as far as number of cases are concerned, with over 5000 cases being consistently reported annually.

RRV causes a disease which is rarely fatal and manifests primarily as acute polyarthralgia. However, the pain in the joints, which can sometimes be debilitating, may persist for weeks after the acute phase of the disease is over. This was the basis for its previous nomenclature, epidemic polyarthritis.

RRV transmission to human beings is associated with the rainy season, when there is an abundance of breeding opportunities for mosquitoes. The main methods to stave off the disease encompasses methods of vector control and vector avoidance.

The virus is named after the Ross river in Townsville, where it was first identified to be the causative organism behind the epidemic polyarthritis.

According to a (translated) report in Free News Volga, the Saratov regions remains active for the transmission of Hemorrhagic Fever with Renal Syndrome (HFRS). In January 2015, as many as 121 people were identified to be suffering from HFRS, which represents a four fold increment to the number of cases reported in January 2014.

HFRS is a group of symptomatologically similar diseases caused by a group of viruses belonging to the family Bunyaviridae. The viruses that cause HFRS include Hantaan, Dobrava, Saaremaa, Seoul and Puumala viruses.

These viruses are primarily carried by rodents and human beings get affected when they come in contact with rodent urine or saliva or even aerosolized dust from rodent nests. Known carriers

include the striped field mouse (Apodemus agrarius), the reservoir for both the Saaremaa and Hantaan virus; the brown or Norway rat (Rattus norvegicus), the reservoir for Seoul virus; the bank vole (Clethrionomys glareolus), the reservoir for Puumala virus; and the yellow-necked field mouse (Apodemus flavicollis), which carries the Dobrava virus.

Control measures, therefore, center around measures for rodent control and exposure limitation. None of the HFRS have a specific treatment and supportive therapy, with maintenance of hydration, electrolytes, appropriate antibiotics to treat any secondary infections and dialysis for renal support being the pillars of disease management. Depending on the causative virus and the patient profile, mortality varies from as low as 1% to as high as 15%.

Leishamaniasis, a disease caused by Leishmania donovani, and spread by the sand fly, is reportedly raging through the capital of the Caliphate held by ISIS, Raqqa, Syria. Newspaper reports contend that there may be as many as 2,500 cases of Leishmaniasis in the city, which has become the focus of military strikes by multiple nations that has targeted it as the stronghold of the ISIS.

The city of Raqqa reportedly lies in ruins and amidst massive shortage of medical personnel and drugs, the outbreak is likely to get worse. This further goes to highlight the impact that social, political and civil unrest has on health, and takes the discourse of infectious disease outbreaks and controls to domains beyond medical issues. Social, economic and political determinants are equally important in deciding the outcome of infectious diseases in today’s world.

A new study from China, published in the Lancet Infectious Diseases journal, contends that a novel, tick-borne Anaplasmosis maybe transmitted from infected goats to human beings in contact. The abstract of the study is given below:

Summary

Background

Anaplasma phagocytophilum and Anaplasma ovis cause human infections. We investigated the potential for human pathogenicity of a newly discovered Anaplasma species infecting goats in China.

Methods

We collected blood samples from patients with a history of tick bite in the preceding 2 months at Mudanjiang Forestry Central Hospital of Heilongjiang Province from May 1, to June 10, 2014, to detect the novel Anaplasma species by PCR. We inoculated positive samples into cell cultures. We characterised the isolated pathogen by morphological and phylogenetic analyses. We tested serum antibodies by indirect immunofluorescence assay.

Findings

28 (6%) of 477 patients assessed were infected with the novel Anaplasma species according to PCR and sequencing. We isolated the pathogen in vitro from three patients. Phylogenetic analyses of rrs, gltA, groEL, msp2, and msp4 showed that the pathogen was distinct from all known Anaplasmaspecies. We provisionally nominate it “Anaplasma capra”. 22 (92%) of 24 patients with data available had seroconversion or a four-fold increase in antibody titres. All 28 patients developed non-specific febrile manifestations, including fever in 23 (82%), headache in 14 (50%), malaise in 13 (46%), dizziness in nine (32%), myalgia in four (14%), and chills in four (14%). Additionally, ten (36%) of 28 patients had rash or eschar, eight (29%) had lymphadenopathy, eight (29%) had gastrointestinal symptoms, and three (11%) had stiff neck. Five patients were admitted to hospital because of severe disease. Six (35%) of 17 patients with data available had high hepatic aminotransferase concentrations.

Interpretation

The emergence of “A capra” as a cause of human disease suggests that individuals living in or travelling to endemic regions in northern China should take precautions to reduce their risk of exposure to this novel tick-borne pathogen.

The causative bacterium of plague, Yersinia pestis, has been detected in fleas in Picture Canyon, Arizona. Deaths of prairie dogs in this region alerted officials to the possibility of the disease.

Prairie dogs are especially vulnerable to this bacterium as they live in social burrows which may be infested with rodents that carry the fleas bearing the disease causing bacteria. Once the host rodent dies, the fleas seek out new hosts to feed off as they are sanguinivorous. It has been noted that even a single infected member of a prairie dog colony may lead to the death of as many as 90% of the members of the colony.

Human cases have been known to develop from close contact with cats that have preyed on infected rodents, and adequate advisory is being issued, especially to campers and hikers in the region, about the risks of plague. In addition, the prairie dog burrows at the affected place, Picture Canyon, are being sprayed with insecticide to kill the fleas that may host the plague bacillus.

According to the report of the Bangladesh Institute of Epidemiology, Disease Control and Research, there have been 9 cases of Nipah virus encephalitis in the country in the first two months of 2015. Of these 9 cases, 6 have died, attributing a 67% mortality to the disease in the current year.

The consumption of fruit and fruit products, primarily date and date palm sap, contaminated with the urine or saliva of infected fruit bats is the main reason behind the disease. Fruit bats, belonging to the Pteropodidae family (Pteropus giganteus) are the most commonly implicated in the transmission of this virus which has a very high case fatality rate. The CFR varies from 40-75% depending on different outbreak areas, and the immediacy of diagnosis and management initiation, which may be a major cause of delay.

Unfortunately, there is no vaccine or specific treatment for this disease and most cases need intense supportive care. The virus emerged first in a cluster of cases in Malaysia, but has been established in Bangladesh, which is currently the only country reporting cases of Nipah virus disease.

The Times of Zambia reports that three persons have died from suspected bubonic plague in the Nyimba District of the Eastern Province. Reportedly 13 people from the Kavyeni village have been affected by the disease in what seems like an ongoing outbreak.

The neighboring countries of Mozambique and Malawi are also suffering from an outbreak of cholera and typhoid, which have broken out in the Mchinji and Kasungu areas of Malawi and since these areas are in close proximity to Chipata, the health authorities have warned the public to be on high alert for the possibility of these diseases occurring within the nation.

While more information is not available according to this report, it needs to be followed up to confirm the outbreak of bubonic plague and institute control measures as needed.